Hermetic sealing system

ABSTRACT

An hermetic sealing system for openings in an enclosure. In one form a cover is provided having an edge fitting over a container having a lip with the cover fitting loosely over the lip of the container. A flexible gasket member is provided between the lip of the container and the edge of the cover. A metal band is provided encircling the mating portions of the container and the cover compressing the flexible gasket between such mating portions. A mastic such as a room temperature cure epoxy is forced into the space between the metal band and the container, the mastic also filling the space between the edge of the cover and lip of the container and moving into contact with the flexible gasket. The mastic is then cured, firmly sealing the cover to the container. If desired, the metal band may be treated with a release agent and then removed after the mastic is cured. In another form, a bushing member surrounds an opening in a wall and is bolted to the wall. A channel in the base of the bushing carries a flexible gasket member compressed against the wall member about the opening. A second channel in the base of the bushing is filled with a mastic which when cured seals the bushing to the wall member.

United States Patent Frey, III

[ 51 Aug. 22, 1972 [54] HERMETIC SEALING SYSTEM [72] Inventor: LangdonT. Frey, 111, Newton, NC.

[73] Assignee: General Electric Company [22] Filed: Nov. 2, 1970 [21]Appl. No.: 85,886

[52] US. Cl. ..220/46 R, 156/69, 220/81 R, 220/85 TC [51] Int. Cl...B65d 53/00 [58] Field of Search..220/46 R, D16. 4, 85 TC, 81 R, 220/46MS; 277/72 FM; 285/294, 297, 53; 292/256.61; 49/475; 156/69, 242, 305

Primary Examiner-M. Henson Wood, Jr.

Assistant ExaminerEdwin D. Grant AttorneyFrancis X. Doyle, Vale P.Myles, Frank L. Neuhauser, Oscar B. Waddell and Joseph B. Forman 1 1ABSTRACT An hermetic sealing system for openings in an enclosure. In oneform a cover is provided having an edge fitting-over a container havinga lip with the cover fitting loosely over the lip of the container. Aflexible gasket member is provided between the lip of the container andthe edge of the cover. A metal band is provided encircling the matingportions of the container and the cover compressing the flexible gasketbetween such mating portions. A mastic such as a room temperature cureepoxy is forced into the space between the metal band and the container,the mastic also filling the space between the edge of the cover and lipof the container and moving into contact with the flexible gasket. Themastic is then cured, firmly sealing the cover to the container. Ifdesired, the metal band may be treated with a release agent and thenremoved after the mastic is cured. in another form, a bushing membersurrounds an opening in a wall and is bolted to the wall. A channel inthe base of the bushing carries a flexible gasket member compressedagainst the wall member about the opening. A second channel in the baseof the bushing is filled with a mastic which when cured seals thebushing to the wall member.

10 Claims, 4 Drawing Figures PATENTEDwczz I972 SHEET 1 BF 2 Y Zmryaavmy, E, @w! 1% $51" 5y HERMETIC SEALING SYSTEM BACKGROUND OF THEINVENTION This invention relates to hermetic seals and more particularlyto an hermetic sealing system for sealing two overlying members.

In many industrial applications, a gas tight joint or an hermetic sealis required between two members. If the members are of metal, many timeswelding soldering or brazing are utilized. An alternative which is alsooften used is the provision of a resilient gasket or packing between themembers together with an arrangement for holding such members togethercompressing the gasket or packing therebetween. One example of this typeof application is a permanently sealed distribution transformer! The useof an insulating oil or other dielectric liquid in the transformercasing which as is well known deteriorates when exposed to theatmosphere requires that the casing be hermetically sealed. When thistype of transformer is properly constructed, no maintenance is normallynecessary for many years. In fact, in many cases before the time formaintenance arrives, the transformer has to be replaced by one ofgreater capacity so that maintenance in the field is not ordinarilyrequired. For the foregoing reason, it is possible to make what isgeSerally termed a permanently" sealed transformer.

In the past, welding has often been utilized to provide a permanent sealwhich has an hermetic feature. However, a welding operation normallyincreases the cost of the transformers and utilities, althoughpreferring permanently sealed transformers, have still largely purchasedgasket sealed transformers since they normally adequately provide anhermetic seal for the transformer and are normally less costly and moreeasily maintained when maintenance is required. Also, with a weldingoperation, the weldment normally presents a corrosion problem which mustbe properly painted or otherwisecoated so as to resist such corrosionand often this is a maintenance requirement of the utility when a weldedjoint is used in transformers. Of course, it will be understood that allentries to the transformer must be hermetically sealed. For example,bushing members are provided for the entry and exit of electrical cableto the transformer. These members must be hermetically sealed to thetransformer.

There has been recently developed many types of plastic adhesives whichcan be utilized to make a suitable hermetic seal. However, many of theseadhesives require a protracted curing period before their full strengthis reached. This long curing period is normally not compatible with massproduction techniques which are used in the manufacture of distributiontransformers. Another problem which is found with the use of plasticadhesives is that they do not provide an adequate vapor barrier toprevent moisture from entering into the sealed transformer.

It is, therefore, one object of this invention to provide an hermeticsealing system for electrical apparatus which can be used by massproduction techniques.

It is a further object of this invention to provide an hermetic sealsuitable for use on electrical distribution apparatus.

A still further object of this invention is to provide an hermeticsealing system which also mechanically secures the overlying surfaceswhich are sealed.

YOFTHEINVENTION Briefly in one form,this invention comprises a containerhaving a lip and a cover having an edge portion which overlies thecontainer lip. A flexible gasket member is placed between the edge ofthe cover and the lip of the container. A metal band is secured to theoverlying surfaces forcing them together and compressing the gasket. Aplastic mastic material is forced between the cover band and theoverlying surfaces filling all spaces therebetween and contacting thegasket. When cured, the plastic material holds the overlying surfacestogether and with the gasket forms an hermetic seal between theoverlying surfaces.

In another form a bushing member is mounted on a wall about an openingin the wall. A first channel in the base of the bushing carries aflexible gasket compressed between the bushing and the wall. A secondchannel is provided and a plastic mastic is forced into the secondchannel between the bushing and the wall, and when cured seals thebushing to the wall.

The invention which is sought to be protected will be particularlypointed out and distinctly claimed in the claims appended hereto.However, it is believed that this invention and the manner in which itsvarious objects and advantages are obtained as well as other ob jectsand advantages thereof will be better understood by reference to thefollowing detailed description of the present preferred embodiment whenconsidered in the light of the accompanying drawings.

BRIEF DESCON OF DRAWINGS FIG. 11 is a plan view with parts broken awayof an electrical distribution apparatus using a preferred form of thesealing system of this invention; and

FIG. 2 is an enlarged partial sectional view showing the preferredsealing system of this invention in greater detail;

FIG. 3 is a sectional side view of one form of bushing member showing apreferred form of the sealing system of this invention used therewith;and

FIG. 4 is a partial sectional view similar to FIGURE 3 showing amodified form of the sealing system of FIGURE 3.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to the drawings in whichlike numerals are I used to indicate like parts and particularly toFIGURE 11, there is shown an electrical distribution apparatus 10, forexample, a distribution transformer, having a tank or container 12 and acover 114. Mounted within tank 112 is a core and coil unit 116 which asshown is submerged in a dielectric fluid 118 which may be, for example,an insulating oil. Tank wall 112 is provided with a plurality of lowvoltage bushings 2t]? while cover I4 has a high voltage bushing 22mounted thereon. As will be understood, it is required to seal the coverM to the tank 112 in an hermetic manner so as to prevent moisture orother contaminates from entering the dielectric fluid I8 and possiblycausing failure of the electrical apparatus lltl. The cover M has anedge 24 which overlies the lip 26 on tank I2. This can best be seen fromFIGURE 2 of the drawing.

bodiment of the invention, the acrylic rubber gasket 28 is vulcanized inplace on the lip 26 in the ledg e 30 in a manner which will be wellunderstood by those skilled in the art.

As is apparent from FIGURE 2, the edge 24 of cover 14 has a portion 32which is similar to ledge 30 on the lip 26. As can be seen, portion 32of edge 24 engages gasket 28 compressing it between ledge 30 and portion32. Of course, if desired, it will be understood that an epoxy cementcould be applied to the gasket 28 so as to adhere to portion 32 of edge24 as the parts are placed together in the manner shown in FIGURE 2.After the parts are placed in overlying relationship with gasket 28compressed between ledge 30 and portion 32 of edge 24, a metal band 34is placed around the overlying surfaces of the lip 26 and edge '24 andtightened in any known manner so as to force the overlying surfacestogether and further compress gasket 28 between ledge 30 and portion 32.After cover band 34 has been tightened, a mastic material 36 is forcedinto band 34 through an opening 38. As will be understood, the mastic 36fills all of the open spaces between band 34, cover edge 24 and tank lip26 as well as all of the spaces between edge 24 and lip 26 until themastic contacts the gasket 28 therebetween in the manner shown in thedrawingrln the preferred embodiment, the mastic 36 may be a roomtemperature vulcanizing silicone rubber material or it may be a roomtemperature curing epoxy resin. Obviously, other types of plasticmaterial may be used as desired.

If the mastic 36 is an epoxy material, it is possible to coat the innerportion of metal band 34 with a release agent. Then when the epoxy 36 isfully cured, the cover band 34 can be removed and reused for makingfurther hermetic sealing systems. As is well know, the epoxy willprovide a strong mechanical bond between cover 14 and tank 12eliminating the necessity for the metal band 34.

As will be understood, the gasket member 28 prevents any of thedielectric fluid 18 from contacting mastic 36 and as is well known thedielectric fluid may cause damage to the mastic 36 depending on the typeof material used. The gasket 28 also prevents any moisture which maypenetrate mastic 36 from reaching the oil 18. As will be understood, theacrylic rubber gasket 28 will prevent any moisture from entering thetank even though it should penetrate the mastic 36.

As will be understood, it is necessary that all openings or entrances totransformer be hermetically sealed. For example, low voltage bushings onwall 12 as shown in FIGURE 1, surround an opening (not shown) in wall12, allowing the low voltage leads to be brought out from thetransformer 10. The hermetic sealing system of this invention may alsobe used to hermetically seal a bushing to a wall member.

FIGURE 3 shows one form of bushing member 50 which is mounted on a wallmember 12a such as the wall of a transformer enclosure, surrounding anopening 52 in wall i2a A plurality of leads 54 are embedded in bushing56 and extend through opening 52 for connection to internal leads (notshown) in a manner well understood in the art In the form shown inFIGURE 3, a plurality of bolts 56 are provided for bolting bushing 50 tothe tank wall 112a. Obviously, other known fastening means could beprovided, if desired. A channel58 is provided in the base 60 of bushing50, surrounding the opening 52 in or otherwise attached to wall 12a,gasket 62 is compressed between bushing 50 and wall 120, forming a sealabout opening 52. After bushing 50 has been tightened, to compressgasket 62, a plastic mastic material 64 is forced through opening 66 inbushing 50 into a second channel 68 formed in base 60 of the bushing 50.As will be understood, mastic 64 completely fills channel 68 and, oncuring, forms a strong bond between bushing 50 and wall 12a. Of course,mastic 64 may be either room temperature vulcanizing silicone rubber ora room temperature curing epoxy resin, as previously discussed withreference to FIGURES 1 and 2. Obviously, other types of plastic materialcould be used, the requirement being that they cure substantially atroom temperature and that they form a strong, hermetic bond betweenbushing 50 and wall 12a.

As shown in FIGURE 3, it is preferred to have two openings 66 in bushing50. One opening 66 is used to force the mastic material 64 into channel68, the other opening shows completion when the mastic 64 appears in theopening. Of course, the same use may be made of two openings 38 in band36 of FIGURES I. and 2.

A modification of the hermetic sealing system of FIGURE 3 is shown inFIGURE 4, which is only a partial sectional view. As shown in FIGURE 4,the bushing 50ais bolted to wall l2aabout opening 52 by bolts 56. Achannel 58ain base 60aof bushing 50a, surrounding opening 52 has aresilient gasket 62'mounted therein and compressed between bushingSilaand wall 12a, as in FIGURE 3. As shown, base 6tlaof bushing 50aisnotched or raised slightly from wall l2aand includes a second channel68awith an opening 66 from the top of bushing Silaproviding access tochannel 68aand the notch in the base 66a. A dam 70 is placed aboutbushing Stlaclosing the notch in base 60a, as shown. The dam 70 may beplastic or metal, as desired. A mastic material 64 is then forcedthrough opening 66 into channel 68aand the notch in base 66a, completelyfilling theopen space between dam 70 and gasket 62. After mastic 64 hascured, it will form a strong bond between bushing SQaand wall 12 a, aspreviously discussed with reference to FIGURE 3.

While there has been shown and described the present preferredembodiment of the hermetic seal system of this invention, it will ofcourse be obvious to those skilled in this art that changes ormodifications may be made without departing from the invention. It isintended by the attached claims to cover all such changes andmodifications as fall within the spirit and scope of the invention.

What is claimed as new and desired to secure by Letters Patent of theUnited States is:

1. An hermetic sealing system for joining a cover to a container inwhich said cover and said container have overlying surfaces comprising aflexible gasket member compressed between said overlying surfaces, ametal band member surrounding said overlying surfaces and pressing saidoverlying surfaces into sealing engagement with said gasket and a roomtemperature curing plastic material completely filling all the spacesbetween said metal band and said overlying surfaces and contacting saidgasket.

2. An hermetic sealing system for sealing an opening in a container inwhich a sealing member is provided overlying said opening, said sealingmember and said container having overlying surfaces comprising a channelformed in one of said overlying surfaces, a flexible gasket membersecured in said channel and compressed between said overlying surfaces,a space provided between said overlying surfaces extending exteriorly ofsaid gasket to the edge of said overlying surfaces, means secured atsaid edge of said overlying surfaces to close said space therebetweenand a room temperature curing plastic material completely filling saidspace between said overlying surfaces and contacting said gasket andsaid means secured to said edge of said overlying surfaces.

3. An hermetic sealing system as claimed in claim 2 in which saidsealing member is a cover for said-container and said means secured atsaid edge of said overlying surfaces is a metal band surrounding saidoverlying surfaces and pressing said overlying surfaces and compressingsaid gasket therebetween.

4. An hermetic sealing system as claimed in claim 2 in which saidsealing member is a bushing, said channel is formed in said bushing andsaid means closing said space between said overlying surfaces is a dammember mounted on said container surrounding and secured to the edge ofsaid bushing.

5. An hermetic sealing system for sealing an opening in a container inwhich a bushing member is provided overlying said opening with saidbushing and said container having overlying surfaces comprising a firstI channel member formed in said bushing and completely surrounding saidopening in said container, a flexible gasket member mounted in saidfirst channel and compressed between said overlying surfaces, a secondchannel formed in said bushing completely surrounding said firstchannel, at least one opening extending from the exterior of saidbushing to said second channel and a room temperature curing plasticmaterial completely filling said second channel and said opening.

6. A method of making an hermetic seal between a cover and a containercomprising,

a. placing a flexible gasket member on the outer surface of the lip ofsaid container,

b. placing said cover on said container with a surface of the coveroverlying a mating surface of said container,

c. placing a metal band in overlying relationship completely surroundingsaid overlying surfaces and tightening said metal band to compress saidgasket between said overlying surfaces and d. completely filling thespaces between said cover band and said overlying surfaces with aplastic 7. e ir iie'thod of making an hermetic seal as set forth inclaim 6 in which said flexible gasket is vulcanized in place to the lipof said container.

8. The method of making an hermetic seal as set forth in claim 6 inwhich said gasket is coated with an epoxy cement, and said epoxy cementhardens to ad here to said overlying surfaces of said container and saidcover.

9. A method of making an hermetic seal between a sealing member and acontainer having an opening therein comprising,

a. placing a flexible gasket member around said opening between saidsealing member and said container,

b. providing securig means between said sealing member and saidcontainer, said securing means drawing said sealing member against saidcontainer and compressing said gasket therebetween,

c. completely filling the space between said sealing member and saidcontainer exteriorly of said gasket with a room temperature curingplastic material.

10. A method of making an hermetic seal between a bushing and acontainer having an opening therein comprising,

a. providing a pair of channels in the base of said bushing,

b. mounting a flexible gasket in one of said pair of channels,

c. securing said bushing to said container with said gasket surroundingsaid opening and compressed between said bushing and said container,

d. completely filling said other channel between said bushing and saidcontainer with a room temperature curing plastic material.

1. An hermetic sealing system for joining a cover to a container inwhich said cover and said container have overlying surfaces comprising aflexible gasket member compressed between said overlying surfaces, ametal band member surrounding said overlying surfaces and pressing saidoverlying surfaces into sealing engagement with said gasket and a roomtemperature curing plastic material completely filling all the spacesbetween said metal band and said overlying surfaces and contacting saidgasket.
 2. An hermetic sealing system for sealing an opening in acontainer in which a sealing member is provided overlying said opening,said sealing member and said container having overlying surfacescomprising a channel formed in one of said overlying surfaces, aflExible gasket member secured in said channel and compressed betweensaid overlying surfaces, a space provided between said overlyingsurfaces extending exteriorly of said gasket to the edge of saidoverlying surfaces, means secured at said edge of said overlyingsurfaces to close said space therebetween and a room temperature curingplastic material completely filling said space between said overlyingsurfaces and contacting said gasket and said means secured to said edgeof said overlying surfaces.
 3. An hermetic sealing system as claimed inclaim 2 in which said sealing member is a cover for said container andsaid means secured at said edge of said overlying surfaces is a metalband surrounding said overlying surfaces and pressing said overlyingsurfaces and compressing said gasket therebetween.
 4. An hermeticsealing system as claimed in claim 2 in which said sealing member is abushing, said channel is formed in said bushing and said means closingsaid space between said overlying surfaces is a dam member mounted onsaid container surrounding and secured to the edge of said bushing. 5.An hermetic sealing system for sealing an opening in a container inwhich a bushing member is provided overlying said opening with saidbushing and said container having overlying surfaces comprising a firstchannel member formed in said bushing and completely surrounding saidopening in said container, a flexible gasket member mounted in saidfirst channel and compressed between said overlying surfaces, a secondchannel formed in said bushing completely surrounding said firstchannel, at least one opening extending from the exterior of saidbushing to said second channel and a room temperature curing plasticmaterial completely filling said second channel and said opening.
 6. Amethod of making an hermetic seal between a cover and a containercomprising, a. placing a flexible gasket member on the outer surface ofthe lip of said container, b. placing said cover on said container witha surface of the cover overlying a mating surface of said container, c.placing a metal band in overlying relationship completely surroundingsaid overlying surfaces and tightening said metal band to compress saidgasket between said overlying surfaces and d. completely filling thespaces between said cover band and said overlying surfaces with aplastic material.
 7. The method of making an hermetic seal as set forthin claim 6 in which said flexible gasket is vulcanized in place to thelip of said container.
 8. The method of making an hermetic seal as setforth in claim 6 in which said gasket is coated with an epoxy cement,and said epoxy cement hardens to adhere to said overlying surfaces ofsaid container and said cover.
 9. A method of making an hermetic sealbetween a sealing member and a container having an opening thereincomprising, a. placing a flexible gasket member around said openingbetween said sealing member and said container, b. providing securingmeans between said sealing member and said container, said securingmeans drawing said sealing member against said container and compressingsaid gasket therebetween, c. completely filling the space between saidsealing member and said container exteriorly of said gasket with a roomtemperature curing plastic material.
 10. A method of making an hermeticseal between a bushing and a container having an opening thereincomprising, a. providing a pair of channels in the base of said bushing,b. mounting a flexible gasket in one of said pair of channels, c.securing said bushing to said container with said gasket surroundingsaid opening and compressed between said bushing and said container, d.completely filling said other channel between said bushing and saidcontainer with a room temperature curing plastic material.